In general, a power-up signal generation circuit serves to reset a semiconductor memory device. A semiconductor memory device operates with an external voltage (VEXT). The external voltage (VEXT) rises from 0 V up to a preset level at a constant slope. At this time, if the internal circuits of the semiconductor memory device are directly supplied with the external voltage (VEXT), they may be adversely affected by the rising external voltage (VEXT) to cause malfunction. To prevent the malfunction, the semiconductor memory device includes a power-up signal generation circuit that generates a power-up signal whose level is changed when a power-up period during which an external voltage (VEXT) rises up to a preset level ends.
Meanwhile, a semiconductor memory device, receiving the external voltage (VEXT), generates various internal voltages, such as a core voltage (VCORE), a peripheral voltage (VPERI), and a bitline precharge voltage (VBLP). The internal voltages used in the semiconductor memory device are designed to maintain preset levels, and the semiconductor memory device may malfunction if the levels of the internal voltages become lower than the preset levels.
Therefore, a known power-up signal generation circuit generates a power-up signal when an internal voltage as well as an external voltage reaches a preset level. For example, if the internal voltage reaches the preset level, the power-up signal generation circuit generates the power-up signal and the semiconductor memory device becomes reset in response to the power-up signal. Further, after the power up process described above is finished, the internal voltage maintains a voltage level higher than the preset level.
However, if a semiconductor memory device performs a high-current-consuming operation, such as a bank active operation or a self-refresh operation, a level of the internal voltage may be lowered to below the preset level, and thus causing the semiconductor memory device to be reset. Specifically, as illustrated in FIG. 1, if an internal voltage VINT is lowered to below the preset level, e.g., a power-up level (1.1 V to 1.2 V), a power-up signal PWRUP may be again enabled to a logic high level to reset the semiconductor memory device, as indicated by “X”.
Meanwhile, even though the internal voltage is lowered to below the power-up level (1.1 V to 1.2 V), the semiconductor memory device may normally operate. However, the known power-up signal generation circuit always resets the semiconductor memory device if the internal voltage is lowered to below the power-up level (1.1 V to 1.2 V).